Cucurbituril-Shaped Cd₁₈(triazolate)₁₂ Unit-Based Metal–Organic Framework Exhibiting an C₂H₂/CO₂ Separation Ability

Herein, a metal–organic framework (MOF), {[(Me₂NH₂)₄]­[Cd­(H₂O)₆]­[Cd₁₈(TrZ)₁₂(TPD)₁₅(DMF)₆]}_n (denoted as JXNU-18, TrZ = triazolate), constructed from the unique cucurbituril-shaped Cd₁₈(TrZ)₁₂ secondary building units bridged by 2,5-thiophenedicarboxylic (TPD^2–) ligands, is presented. The formation of the cucurbituril-shaped Cd₁₈(TrZ)₁₂ unit is unprecedented, demonstrating the geometric compatibility of the organic linkers and the coordination configurations of the cadmium atoms. Each Cd₁₈(TrZ)₁₂ unit is connected to eight neighboring Cd₁₈(TrZ)₁₂ units through 30 TPD^2– linkers, affording the three-dimensional structure of JXNU-18. More interesting is that JXNU-18 displays an efficient C₂H₂/CO₂ separation ability, as revealed by the gas adsorption experiments and dynamic gas breakthrough experiments, which afford insights into the potential applications of JXNU-18 in gas separation. The tubular pores composed of two Cd₁₈(TrZ)₁₂ units bridged by six 2,5-thiophenedicarboxylic linkers provide the suitable pore space for C₂H₂ trapping, as unveiled by computational simulations.